Divulging the potential role of wide band gap semiconductors in electro and photo catalytic water splitting for green hydrogen production

Abstract

ABSTRACT

Green hydrogen is the most promising option and a two in one remedy that resolve the problem of both energy crisis and environmental pollution. Wide band gap semiconductors (WBG) (E_g >2 eV) are the most prominent and leading catalytic materials in both electro and photocatalytic water splitting (WSR); two sustainable methods of green hydrogen production. WBGs guarantee long life time of photo charge carriers and thereby surface availability of electrons and holes. Therefore, WBG (with appropriate VB-CB potential) along with small band gap materials or sensitizers can yield extraordinary photocatalytic system for hydrogen production under solar light. The factors such as, free energy of hydrogen adsorption (ΔG_H*) close to zero, high electron mobility, great thermal as well as electro chemical stability and high tunability make WBG an interesting and excellent catalyst in electrolysis too. Taking into account the current relevance and future scope, the present review article comprehends different dimensions of WBG materials as an electro/photo catalyst for hydrogen evolution reaction. Herein WBG semiconductors are presented under various classes; viz. II-VI, III-V, III-VI, lanthanide oxides, transition metal based systems, carbonaceous materials and other systems such as SiC and MXenes. Catalytic properties of WBGs favorable for hydrogen production are then reviewed. A detailed analysis on relationship between band structure and activity (electro, photo and photo-electrochemical WSR) is performed. The challenges involved in these reactions as well as the direction of advancement in WBG based catalysis are also debated. By virtue of this article authors aims to guideline and promote the development of new WBG based electro/photocatalyst for HER and other applications.